1. Field of the Invention
This invention relates to a ball bearing, and more particularly to a ball bearing suited for a usage condition in which a high moment load is dominant and a rolling-contact fatigue life (flaking life, that is, life until generation of flaking) is required, for example, suited as the wheel bearing of the semi-float type rear axle of an automotive vehicle.
2. Description of the Prior Art
It has heretofore been proposed to make the bearing orbit non-circular so as to be capable of withstanding the high moment load of a bearing.
However, in the case of a bearing such as the wheel bearing of the semi-float type rear axle of an automotive vehicle in which the moment load condition is severe, the point of contact between rolling members (hereinafter referred to as the balls) and the orbit groove is moved to near the groove shoulder and part of the contact ellipse at the point of contact protrudes from the orbit groove (hereinafter referred to as the riding of the balls), thus causing a problem before the life of the bearing. When the riding of the balls occurs, streaks are created on the surface of the balls and obstructions such as noise and vibration arise.